Fig. 3.

Phylogenetic tree of 32 Iraqi isolates and 24 reference strains of infectious bronchitis virus based on the nucleotide sequences of the S1 gene. The phylogenetic tree was constructed, using MEGA version 5, by the neighbor-joining method with 1000 bootstrap replicates (bootstrap values are shown on the tree). The isolates from this study are indicated by black circles. White dots indicate Iranian reference strains, and black triangles indicate Iraqi reference strains